Electric furnace.



R. S. BICKNBLL.

ELECTRIC FUBNAGR f Arrmouron ifILBD 001225. 1913.

` Patented Apr. 21, 1914.

INVENTOR.'

WITNESSS UNITED STAILIIS PATENT orales.

ELECTRIC FURNACE.

Specification of Letters Patent.

` Patented Apr. .21, 12H4.

Application filed October 25, 1913. Serial No. 797.191.

To all tv/wm it may concern Be it known that I, RICHARD STUART Brok- NELL, a citizen of the United States, residing at New York, in .the county ovfN'ew York and State of New York, have invented lcervtain new and useful Improvements in Eiec'- rent, the resistance' of the circuit or circuits lg/comprised by the resistor is raised` or lowered, is combined with one Vor more nonmetallic resistors similar or otherwise. The non-metallicl resistors that .I .use;are carbon resistors, graphite resistors, etti-1, i t

My invention is not limited to'electrie furnaces but may be applied tovelecztrlicfovens, etc.- 1

It has been found that the `rsistance of the resistors in electric furnaces of the-re-v sistance type is not usually dependable,L

This is due, primarily', to twoicauses, (l) the lack of uniformity ofithc resistancemateriaLs ordinarily employcd'for rcsistorsii l v(52), the lalterations vdue to' the passage'jofj the current through them while' in "operation, In order 'to meet these requirements and ob tain a'furnace capable of operating on vari-V ous capacities, and a't the desired tempera-Y tures; 1n other words, capabl(` of reguiatlon and adjustment. some means must-be" em- [,loyed sothat the desired amperage may he ohtainedas simply and quickly as possible. In the past, this has been ordinarillyy accom plished by regulating the voltageon the .fur-

nace terminals;` This regulatioxrof volta l'c has been accomplished by a transformer elivering several voltages on the secondary or by means of a generator capable of delivel-ing,r various voltages according to the requirements. Another method of regulation which consists in altering the resistance per unit of length 0f the resistor has likewise been employed. Y

The practical utility ofmy invention consists, in most cases, in dispensing with machinery for purposes of regulating andadjusting the furnace. A furnace according,r to m invention can be operated on direct or a ternating current. When alternatingY current. is used the furnace is usually operated without a transformer having numero'us taps for regulation and adjustment. As a specific illustration, a furnace may bc designed in accordanccvwith my invention so 4that it may be operated on a line. of "220 volts, alternating or direct current Vwithout; Va' regulating transformer or regulating Vdynamo electric machine. My invention also possesses the following advantages; it permits of cheap construction, ease of operation, and excellent regulation and heat distribution.

Iwill now describe my invention in dhtail, nsing'fo'r the purpose diagrammatic drawings, 'Figures' 1 toG, inclusive. but it is to be understood that. my invention is in no way limited toy such, lor arrangements `of Suchdrawings. Y'

. Fig. 1 shows two similar branched resistors4 Af-an`d B embodying theprinciple of my invention, and each resistor )las three v`rbrancheal, 2, 3, and 7., 8 9 respectively.

The electrodes or terminal-connections It. 5, -.G.*10, 11i, 12m-e connected as shown. With 'these resistorsl a number of arrangements are ssible, but for purposes of' illustration of t e principleV of my invention, the possible arrangements of one branched resistor, will be considered first. In the .resistor A. let the branch 1 have a resistance of 'one ohm, the branch 2 `a resistance of two ohms, and the branch 3 a resistance of three ohms. With the resistor A there is a possibility of six arrangements as follows: (1) with the terminals of a direct current line onv the electrodes 4 and 5,`the `resistance of the circuit consists offthe two branches 1 and 2, having rcsistances of one and two ohms respeetively` makes the total resistance of that ,portion of the circuit comprised by theresistor thv-ee ohms. (2) Similarly, the terminals ot the line may be connected to 4 and 6 which makes the resistance four ohms, and (3) to 5 and which makes the rcsistf ance five ohms. (4) Also, electrodes 5 and. 6 may be connected to the positive terminals of the line, and 4 to the negative terminal of the line. Tn this ease the resistance of the resistor will be two and one-fifth ohms. (5) )Vith 4 and 5 connected to the positive terminal and 6 to the negative, the resistance of the resistor will be three and twothirds ohms. (6) With 4 and 6 connected to the negative terminal, and 5 to the negative the resistance of the resistor-will be two and three-quarters ohms. It will then be seen that for this branched resistor, the con- B, any type trtypes of resistors may be "usc with direct current, butmay be ein: ployed with'alternating current. However,

bination \\'itli'the"iesistor -A, arranged in,

rangements, 1t wilfr'eadilybe seen' that'a number (1t/arrangements to `secure different resistances, are possible. For the resistor substituted and this ,combination will still' be in accordanceiwlith my'invention.

By employing two or more branched re-4 sistors in groups, or by arranging branched resistors with the known types of resistors, it is possible to obtain a wide range of resistances in a set of resistors with practically any interval between the diierent resistances as is desired. Tofaccoinplish this purpose, the resistors may be arranged in parallel or in series, or in groups in parf allel, each parallel groupV connectedin se'-` ries, or in any other suitable manner.

Figs. 2, 3, 4, and 5 show a number of types of single resistors Awhich may be combined in any suitable way. Y i' Fig. 6 shows a combination o'f'fo'ur resistors which is a Y,flexible and desirable arrangement. A

As stated, my inventionis'not limitedto when alternating current Y is employed, to obtainhigh power factors, the number of resistors should bel equal to a w-liole multiple of the number of phases, and this multiple is ordinarily 1, 2, 3, or 4, but it is to be' unde rstood that my invention is not limited to such specific application. "j

Frequently a. number of electrodes are grouped and serve the purpose'of one, so'the specification includes a plurality of elec,A

gle electrode to accomplish the same purpose, A plurality of electrodes,`=

substantially. substantially adjacent, and permanently electrically connected, are also considered as' one electrode in this specication. Any suitable terminal electrical connections of the resistors are also considered as electrodes.

Having thus fully and clearly disclosed theanature of my invention, whatI claim as new 'and'desire to secure 1s: f

1. In an electric furnace ofthe resistance type, the combination of a non- -etallic re- "sistor, having more than two elec ro'des, and arranged'in' such a manner so that by changingfthepiithof the current the resistance fof that portion of the circuit or circuits comjprised by the resistor is raised'or lowered, .with one or more non-metallic resistors.

2. In an electric furnace of the resistance type, the combination of a non-metallic resister,Y which has morev than two electrodes, `and which is arrangedin such a manner so that by changing the path ofthe current the lresistance of that portion of the circuit or circuits comprised by the resistor is raised Vor lowered, with oneor'more similar non- Ametallic resistors.

3: In'an'electric type, branched non-metallic resistors, arranged so. that by changing the'path of the 'current the resistance of that portion of the ,circuit or`circuits comprised bythe resistors 1s :raised or lowered, and each of which resistors has more thantwo electrodes.

In testimony whereof, I have signed my 4'name in thepresenoe of two subscribingwitnesses. l

RICHARD STUART BicKNnLL.

' Witnesses:

' MARX Hnzsci,

furnace of the resistance meaning of the word electrode in this ALCAR ,Hmscrn the employment of a plurality of` `which are 

